1. Field of the Invention
The present invention relates to a part of an operating key device such as the ten-key pad fitted to a telephone, a fax machine, or the like.
2. Description of the Related Art
A main apparatus such as a telephone or a fax machine is fitted with an operating key device such as a ten-key pad, which can be operated to enter a receiver's number or start a function. The operating key device may have a push button structure as shown in FIG. 5 (for example, refer to Patent Document 1).
FIG. 5 is an explanatory drawing for explaining the structure of a single operating key device. The operating key device 100 includes a key 110, hinges 120, a frame 130, and a tact switch 140. The key 110 includes a key top 110A and a flanged part 110B.
The outer wall 200 of a main apparatus has a hole 210 formed through it. The key top 110A protrudes through the hole 210 from the inside of the outer wall 200 to the outside of the wall. The flanged part 110B restricts the protrusion of the key top 110A from the hole 210. The flanged part 110B supports a protrusion 110C on its back side. The protrusion 110C protrudes from the backside of the flanged part 110B toward the tact switch 140. The protrusion 110C pushes the tact switch 140 by moving in the direction Y1 in which the key top 110A can be pushed.
The frame 130 supports the key 110 as floating by means of the hinges 120 and is fixed to the outer wall 200. The tact switch 140 is connected to a circuit board, through which it outputs to the controller of the main apparatus a signal indicating whether an entry operation has been performed. The key 110, hinges 120, and frame 130 are molded integrally out of thermoplastic resin.
FIG. 6 shows an operating key device of last years. In order for this device to be improved in design, its key includes a key top 310A and a hinge key 310B which are separate from each other, and the key top 310A is formed of transparent resin. The key top 310A and hinge key 310B are separate from each other because, if the whole key were formed of transparent resin, the inside of the operating key device would be visible, so that the device would not be desirable in design, and because transparent resin has a property not suitable for the formation of a thick member.
The front side of the hinge key 310B comes into contact with the key top 310A in the direction opposite to a direction Y1 so as to hold the key top 310A between it and an outer wall 200. The hinge key 310B has a protrusion 310C formed on its back side, which pushes a tact switch (not shown). The hinge key 310B is supported as floating through hinges 320 by a frame 330. The front side of the key top 310A is coated in color and shows a number or the function of the operating key. The contact surfaces of the key top 310A and hinge key 310B are flat to have a good appearance to the user.
In FIG. 6, which shows the operating key device 310 as fitted to a main apparatus, the front sides of the frame 330 and hinge key 310B are not flush with each other. However, the front sides of the frame 330 and hinge key 310B have conventionally been designed to be flush with each other so that the key top 310A can be mounted easily on the front side of the hinge key 310B.
An operating key part consists of the hinge key 310B, hinges 320, and frame 330 and is molded integrally out of thermoplastic resin. The operating key part is kept with its front side up on a keeping tray or the like after it is molded integrally and until it is fitted to the main apparatus.    Patent Document 1: JP 2000-311544 A